He said police arrested the two drivers, a 24-year-old Thai and 23-year-old Vietnamese, and they confessed. They face charges of illegally transporting animals, unlicensed trade of animals and cruelty to animals. They could also be charged with transporting unvaccinated animals.

"They were hired to drive the vehicles to the border, where the dogs would be sent off to Vietnam," Detchai said.

Police said 31 of the dogs were dead and the remaining 89 will be taken to a center that cares for rescued dogs in Nakhon Phanom, 370 miles (600 kilometers) northeast of Bangkok.

In mid-August, about 1,800 dogs were rescued from smugglers in Nakhon Phanom, police said.

Their rescue made national news and after learning of their sad state Thais donated more than 20 million baht ($667,000) to help the animals.

Thai media reported on Tuesday, however, that as many as half of those dogs had died at the center because they arrived in such poor health.

Dog meat is a delicacy in Vietnam and is served at restaurants in some parts of the country's north.